Temporal analysis of REM sleep after nest-building behavior in nulliparous albino rat

EEG recording was performed, during nest-building behavior (NBB), from the hippocampus and sensorimotor cortex of nulliparous albino rats with simultaneous recordings of EMGs of neck-muscle and eye movements. The duration of NBB varied with a period of 4-5 days. However, the relative durations of behavioral transitions in NBB, i.e., nest-building, grooming, and sleeping, were regular in both long lasting and early terminated NBB. REM sleep was identified, in every instance, immediately after NBB. The latency of REM sleep was significantly tied to the termination of NBB without regard to the duration of NBB. Differences in the duration of NBB, however, affected REM-propensity: the longer the NBB was, the shorter the latency of REM sleep tended to be. NBB might accelerate the induction of the physiological condition responsible for REM sleep generation.